I. Field of the Invention
The present invention relates generally to conveyors and, more particularly, to a lift and carry accumulating conveyor.
II. Description of the Prior Art
There are a number of previously known lift and carry conveyors for transporting various types of parts along a conveyor line. These previously known lift and carry conveyors typically comprise a pair of spaced apart and parallel stationary rails as well as at least one movable rail which extends generally parallel to the stationary rails.
The movable rail is movable both between a forward and a retracted position as well as between an upper and a lower position. Thus, in order to convey parts supported by the stationary rails along the conveyor line, the movable rail, when in its retracted and lower position, is first moved to an upper position thus lifting the parts up from the stationary rails. The movable rail is then moved to the forward position and, thereafter, to the lower position. When the movable rail is moved to its lower position, the parts are again placed upon the stationary rails so that the parts are effectively transported along the conveyor line by a distance equal to the stroke of the movable rail between its forward and retracted position. The movable rail is then moved to its lower retracted position and the above cycle is repeated.
One disadvantage of the previously known lift and carry conveyors, however, is that such conveyors are only capable of transporting parts along a straight conveyor line. Consequently, when it is necessary to change the direction of the conveyor line, a complex transfer mechanism is also employed to move the parts from one straight conveyor and to a second straight conveyor line.
A still further disadvantage of these previously known lift and carry conveyors is that one drive mechanism is employed to move the movable rail between its forward and retracted position while a second drive motor is used to move the movable rail between its upper and its lower position. The two drive motors must necessarily be synchronized with respect to each other in order to provide required sequential movement of the movable rail relative to the stationary rails. The use of two drive motors, together with the required synchronizing means, disadvantageously increases the complexity and cost of the overall lift and carry conveyor.